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Shouldn't we be cautious of this new technology?
The technology is not new. We have been using radio waves in general for over 100 years and radio in the microwave region for 60 - so the science community has had plenty of time to investigate radio and its health effects.
Nevertheless, the UK has adopted a precautionary approach on radio frequencies by, among other measures, using the International Commission on Non-Ionizing Radiation Protection (ICNIRP) exposure guidelines for the general public. These are five times more stringent than the previous UK NRPB standards. Such standards are based on the only scientifically established effect of radio waves - the 'heating' effect. |
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What happens if a household is near to several different transmitters at the same time? Would the combined exposure be dangerous?
In order to reassure the public, the Radiocommunications Agency (RA) - now part of Ofcom - carries out annual surveys of radio field strength near mobile phone masts. These checks, at the suggestion of the Stewart Report of 2000, number about 100 a year and are carried out at schools and hospitals.
So far, the highest reading Ofcom has recorded was one 279th of the UK exposure guidelines (ICNIRP). Nevertheless, this reading was unusual because the vast majority of sites Ofcom has monitored are thousands of times below the guidelines.
Because these figures are all so tiny and because of the way that radio transmitters work, it is fair to say that - provided they are engineered to comply with ICNIRP guidelines, evidence for which all operators are obliged to provide with each planning application - that even combined signals from several sites at once will still be well within limits. Put another way, if you multiply a very small amount by a few times, you still end up with something very small.
It is also worth remembering that the safety limits follow a precautionary approach and are far below the levels at which an effect of any sort has ever been detected in replicated scientific experiments. On top of this Orange assume 'worst case' figures in all its calculations, which gives a further margin of safety in typical situations. |
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What is a 'beam of greatest intensity'?
Radio waves from all telecoms transmitters are focused to avoid wasting radio energy by beaming signals into the ground or sky. Just like the light from a reflector spotlight, the radio energy is stronger in some places than others.
Equally, however - and again just like a light bulb - the power in the 'beam of greatest intensity' still falls off very steeply, even only a few yards away from the mast. |
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Isn't the difference that mobile phones use 'pulsed' radio waves?
That mobile phone radio signals have health effects because they are 'pulsed' is a suggestion that has little basis in the experimental research carried out in this area.
All radio waves are to some degree altered or modified ('modulated' in the jargon) otherwise they would carry no useful information. Without modulation, a signal would be a bit like a human voice singing a single note rather than speaking words. However, in order to communicate by speech we modulate our voices to create words.
In the case of radio waves, there is no persuasive scientific evidence that the modulation employed by mobile telephony equipment affects human health. |
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Do mobile phone transmitters interfere with other electrical devices?
Interference of devices with the operation of others is highly regulated by governments. Most modern electrical devices are screened against interference from radio waves at the levels experienced in the neighbourhood of radio sites.
However, radio waves emitted in the close proximity of mobile phones could, in principle, interfere with the operation of some electrical devices. This is why people are asked to switch off their phones in hospitals and in aeroplanes. |
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Do masts affect members of the public who wear pacemakers?
Generally, no. Click here for more information from the Medicines and Healthcare products Regulatory Agency. |
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What are radio waves?
Radio waves are a natural form of radiation similar to light. However, for communication use, radio waves are modified to carry messages. |
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Can radio waves affect human health?
The only known effect of radio waves - at the frequencies we use - is the so-called 'heating effect'. There is no other known mechanism by which radio waves can affect human tissue.
Some research has hinted at the possibility of biological effects from handsets at exposure levels below health guidelines. Examples of this were mentioned in the Stewart Report of 2000.
More recently, research from Sweden has linked the use of mobile phone handsets for over 10 years, to a very small increase in the chance of contracting a non-cancerous tumour known as an acoustic neuroma. No effect was reported in a similar study in Denmark.
At the time of writing, these results have yet to be properly established.
But it was because of this research that the UK adopted the precautionary approach mentioned above. |
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What is the 'heating effect'?
It is fair to think of a radio transmitter as a bulb that emits a form of invisible light. Just like the radiation from a light bulb, radio waves from a powerful radio source like a big TV transmitter or radar can heat up human tissue if placed too close.
This heating effect is caused by the ability of radio waves to make molecules vibrate more actively - a quality which was discovered in World War Two during research into radar.
However, mobile transmitters are placed on masts or in other high and inaccessible places. It is, as a result, no more possible for the public to suffer a heating effect by getting too close to a phone transmitter - than it is possible to get burnt by touching the bulb of a street lamp. |
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How close do you have to be to experience the heating effect?
That depends on the power of the transmitter but, in the case of our masts, the distance would normally be about two feet (0.5m). As an added precaution, safety zones as large as 11 yards (10m) are in force around some, depending on their size and output, to protect people from the heating effect.
Nevertheless, radio energy falls away dramatically as the distance between you and the source increases.
This is because of the so-called 'inverse square' law. If you double the distance away from a radio source, you decrease the power by four times. Double that again and the power has fallen by a factor of 16, and so on. |
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What about biological effects?
There are suggestions in some research that radio waves could have a biological effect not related to heating. A biological effect is any observable change in the behaviour of a tissue sample - or living organism - due to an external stimulus.
A biological effect may or may not be harmful. A sound wave causes a biological effect - a physical interaction with your eardrum which in turn sets off a series of chemical and electrical impulses within the brain that you experience as a noise. This is not normally considered harmful. Conversely, sitting in the sun for too long causes a biological effect, which, because of the strength of the sun's rays, can be very harmful indeed.
In the case of radio research no experiment showing a biological interaction with tissue or blood has so far been successfully repeated. This must therefore cast doubt both on the original experiments - and the suggested mechanisms by which radio waves affect biological material. |
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How do I know whether to be worried by an article in the media?
To get some idea of whether a science report quoted in the media is actually serious research or simply idle speculation, there is one simple question you can ask:
Has the research and its conclusions been published in a reputable scientific journal?
Getting research work published is an essential component of the scientific community's own independent quality checking mechanism known as 'peer review'.
Work which has not been published in a refereed journal should be treated cautiously as it has not been scrutinised by independent experts.
peer review
For more information on science's own independent quality control system, select a link below:
www.senseaboutscience.org.uk
www.sciencemediacentre.org
www.parliament.uk |
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Shouldn't we use the precautionary approach in dealing with phone masts?
We do. The Stewart Report of 2000 said, "The balance of evidence to date suggests that exposures to RF radiation below NRPB and ICNIRP guidelines do not cause adverse health effects to the general population."
But then later adds, (1.19) "We conclude therefore that it is not possible at present to say that exposure to RF radiation, even at levels below national guidelines, is totally without potential adverse health effects, and that the gaps in knowledge are sufficient to justify a precautionary approach."
(1.20) "In the light of the above considerations we recommend that a precautionary approach to the use of mobile phone technologies be adopted until much more detailed and scientifically robust information on any health effects becomes available."
It went on to recommend measures, including the following, on precautionary grounds.
The (tougher) ICNIRP guidelines for public exposure be adopted for use in the UK rather than the UK's NRPB guidelines. (The NRPB then adopted ICNIRP as its own figures.)
An independent audit of base stations be carried out to ensure that exposure guidelines are not exceeded outside the marked exclusion zone.
The 'beam of greatest intensity' - the main path of the radio waves from masts - should not fall on any part of a school without agreement from the school and parents. Similar considerations should apply to macrocell base stations sited near to school grounds.
Most were added to Government - and therefore operator - policy (with the exception of the recommendation relating to the 'beam of greatest intensity').
The audit of base stations has been carried out by the Ofcom. They have undertaken an audit every year since the report, producing results in 2001, 2002 and 2003. So far, the highest signal they have encountered was still hundreds of times below the ICNIRP guidelines. The majority of results were thousands of times lower. |
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What research is there?
To date, the World Health Organisation (an international body set up to collect the best medical knowledge from around the world) is aware of over 20,000 good quality studies on this topic, the huge majority of which show no link between mobile phone technology and public health. It concludes:
"Extensive research has been conducted into possible health effects of exposure to many parts of the frequency spectrum. All reviews conducted so far have indicated that exposures below the limits recommended in the ICNIRP (1998) EMF guidelines, covering the full frequency range from 0-300 GHz, do not produce any known adverse health effect. However, there are gaps in knowledge still needing to be filled before better health risk assessments can be made." www.who.int
Set against this is a limited number of research findings, many of which are based on research that has yet to complete peer review or reproducibility tests (see above) and which only suggest biological effects - much less prove that they are harmful. |
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Doesn't all this research suggest that the authorities are worried and that we are right to be as well?
Most existing research was begun in order to fill gaps in existing knowledge and to respond to public concern. |
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What is the difference between good and bad quality science?
Good research follows a well established pathway to its final adoption - or rejection - as a serious contribution to the scientific field of which it forms a part.
To gauge the quality of a piece of research, it is important to understand the how this happens. Adoption is generally viewed as a three-stage process consisting of:
1. the research itself
2. publication (during which it must undergo peer review - or review by colleagues)
3. replication by other scientists
1. Research
This begins with a review of 'research design' - the task of working out how to answer the question being posed. Issues considered include the quality and nature of the methods to be used and any possible 'confounding factors'.
Confounding factors are anything that can make research results unreliable. A good example in epidemiology research is the factor of age.
At first glance, for instance, it might appear worrying that cancer appears to becoming more frequent in some Western societies. However, the problem appears very differently if one takes account of the fact that these same societies have an increasingly large population of elderly people who proportionately are much more likely to suffer from that illness.
Once these problems of this sort are resolved or accounted for the research can proceed. In the case of research into radio waves and human health, guidelines and advice from the WHO exist to help would-be researchers standardise the way they conduct research. This is not to influence the outcome but to help make sure that mistakes from previous work are not repeated.
2. Publication and peer review
Once finished, researchers submit a draft summary of their results to a respected academic journal ranging from Nature, the New England Journal of Medicine or the British Medical Journal at the general end of the spectrum to more specific titles like Bioelectromechanics at the other.
All such journals have an editorial board of scientists - normally working for free - who consider issues such as whether the methods used were appropriate for the research, and whether the conclusions and interpretations appear valid - based on the method and results described. They will also be trying to confirm that the researchers have taken into account other recent developments in the field and got their maths right.
Crucially, they also want to determine whether the method (through which results have been achieved) is described in enough detail for other scientists to attempt to repeat the work and its results.
Researchers are given the opportunity to respond to the reviewer's comments before publication so if work is not in the end published in any reputable journal it will normally be because reviewers and editors do not feel confidence in it.
Although peer review is trusted around the world and has been found effective for generations there can, very occasionally, be instances of editorial bias or pressure on editors to respond to controversy, so it is the final stage - replication - that is normally taken to be the most important hurdle through which research needs to pass for acceptance.
3. Replication - can the research be repeated?
After publication, other scientists around the world try and repeat the experiment to see if the results can be replicated under identical conditions.
If they can't, the research must be rejected on the grounds that the results are random - or caused by mistakes or bias during the experiment.
Some of the research that gave concern to the Stewart Committee, for instance, has now been tested in this way and has not been supported by the new results.
Acceptance as valid new information
If an experiment proves reproducible (and the methods used in the experiment are accepted) then the research is considered to be a valuable addition to the field - and a reliable base on which to carry out further study. |
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Aren't children more vulnerable?
In a recent review of existing research in Holland (Health Council of the Netherlands, 28 January 2002) the Council concluded that: "It is unlikely from a developmental point of view that major changes in brain sensitivity to electromagnetic fields still occur after the second year of life.
"The Committee therefore concludes that there is no reason to recommend that mobile telephone use by children should be limited as far as possible." (The field strength from masts in public areas is generally many thousands of times lower than the exposure from handsets in use.)
UK, June 2000. In their Clarification of Issues Discussed, the IEGMP (Stewart Committee) stated, "In giving special attention to schools, the Expert Group was responding very largely to public concern rather than any proven health hazard".
and
"Since there are no scientific grounds for setting guidelines below the levels set by the International Commission for Non-Ionizing Radiation Protection (ICNIRP) for the public, the Expert Group avoided setting exposure limits for school buildings and grounds below these limits.
For the same reason it did not wish to recommend that there should be a particular distance between a base station and a school."
In January 2005 The NRPB report "Mobile Phones and Health Volume 15 No.5 2004" stated that, "in the absence of any new research specifically focussing on children since the original Stewart Report of 2000, the Stewart Report's precautionary approach to children's use of mobile phones should be maintained". |
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Should I be worried about cancer clusters?
To date, no link has been established between radio transmitter sites and so called 'cancer clusters'. In fact, most research has shown an absence of such a link and, in addition, there is still no known mechanism by which radio waves could initiate cancer.
If radio waves at very low transmission levels actually did cause cancer, it would now be evenly distributed across all urban areas and perhaps the country as a whole. This is because there are several tens of thousands of radio and TV masts of various sorts and most of these are in heavily built-up areas.
There would also be highly worrying cancer 'hotspots' near well established and vastly stronger transmission sources - like TV transmitters - which can be up to 10,000 times more powerful than a phone mast.
See also the 1996 statement by the UK's Independent Committee on Medical Aspects of Radiation in the Environment (COMARE).
http://www.comare.org.uk/comare_faq.htm
More generally, however, it is possible there will be increased numbers of cancers near some radio phone masts for three entirely statistical reasons:
It is an absolute statistical certainty that there will be more cancers of a given type in some places than in others. There will also be other locations with a lot fewer. However, these, unsurprisingly, don't tend to attract public attention.
There are masts more or less everywhere in the UK, so wherever an increased number of cases should appear, the chances are that there will be a mast somewhere nearby.
Most masts are placed in the centre of communities where naturally there will be a more people and so greater concentrations of various medical disorders.
Currently, the best plain English description of cancer clusters - and particularly the conditions under which they may or may not be said to exist - can be found on the website of America's internationally recognised Centre for Disease Control (CDC) in Atlanta, Georgia. |
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What does SAR mean?
SAR stands for 'specific absorption rate'. It is an international standard measure of the amount of radio frequency energy absorbed by your head and body when you use a mobile phone.
The independent Stewart Report of 2000 recommended that each mobile phone model sold in the UK should display an SAR value. This information is intended to help you make an informed choice when you purchase a mobile phone.
Some models of phone have higher SAR values than others. Nevertheless, variations in SAR do not mean variations in safety, as all mobile phones sold in the UK must comply with the international exposure guidelines.
Orange believe that existing and potential customers should be fully informed about SAR values and provide these for all phones used on the Orange network - wherever they are available from the manufacturers. However, because SAR values are provided to us by the mobile phone manufacturers, Orange are not able to guarantee their accuracy.
All mobile phones sold for use on the Orange network have a maximum SAR value of 2 W/kg.
The actual SAR value of a handset varies considerably with the circumstances of its use. If talking to a nearby base station it does not have to 'shout' so loudly and the handset decreases its transmitted power by a factor of up to a thousand to preserve battery charge. As a result, your SAR exposure from a handset is considerably less if you are near a base station.
For further information about specific phone SAR values please visit the website of the relevant phone manufacturer.
www.alcatel.com
www.sony-ericssonmobile.com
www.motorola.com
www.nokia.com
www.mcuk.panasonic.co.uk
www.consumer.philips.com/mobilephones/
www.siemens-mobile.de
www.sony.com
www.trium.net
Mobile Manufacturers Forum (MMF)
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